Department of Physics and Astronomy, UCL

Abstract

The cosmic microwave
background (CMB) is the left-over heat from the Big Bang. This radiation
provides a picture of the universe when it was only 400,000 years old. Now, 14
billion years later, it has cooled to microwave frequencies and is nearly
uniform. The slight variations of 1 part in 100,000 in its temperature reflect
initial inhomogeneities in the matter and radiation that later collapsed to
form clusters and galaxies. These fluctuations carry information about the
origin, composition and evolution of the universe, and theories of the origin
of the universe make detailed predictions about their statistical properties. The CMB is therefore our best hope of uncovering
fingerprints of the physics operating at very high-energy scales, inaccessible
to Earth-bound particle accelerators. Current cosmological data are, for the
first time, precise enough to allow detailed tests of models of the very early
universe. The Planck satellite has then dramatically sharpened our view of the
early universe, and provided a window into the origin of cosmic structure. I
will describe how the Planck data progress our understanding of the extreme
physics of the very early universe, and what we have yet to learn.

Biography

Hiranya Peiris obtained
her undergraduate degree in physics from the University of Cambridge, and her
Ph.D. in astrophysics from Princeton University. She is currently a Reader in
Cosmology at UCL. Previously, she was a Halliday Fellow at the Institute of
Astronomy at the University of Cambridge, having been a Hubble Postdoctoral
Fellow at the University of Chicago prior to that. Her main research interests
are in cosmology, the study of the basic characteristics of the universe (its
contents, history, evolution, and eventual fate), and she spends much of her
time studying the properties of the oldest light we can see in the universe to
understand why and how the Big Bang occurred. She is also interested in how galaxies
form and evolve, and in determining the structure and properties of our Galaxy,
the Milky Way.